Fastener system including a swage fastener and tool for installing same

ABSTRACT

A fastener system for multi-piece swage type fasteners, including a pin and a collar, and providing a stump type fastener constructed to be set as a pull type fastener with the fastener pin having a threaded gripping portion and including an installation tool having a swage anvil and a rotary nut member adapted to be threaded onto the threaded pull portion of the pin whereby a relative axial force is applied between the pin and the collar via the nut member and swage anvil to cause the anvil to radially overengage the collar to swage it into locking grooves on the pin and the pull portion remaining on the pin after installation.

This is a division of U.S. patent application Ser. No. 08/189,871, FiledFeb. 1, 1994 U.S. Pat. No. 5,548,889, which issued Sep. 27, 1996, whichwas a continuation of Ser. No. 7/765,399, filed Sep. 24, 1991, U.S. Pat.No. 5,315,755, which issued May 31, 1994, which was a continuation ofSer. No. 07/654,412, filed Feb. 11, 1991, now abandoned, which was acontinuation of Ser. No. 07/359/482, filed May 31, 1989, now abandoned.

SUMMARY BACKGROUND OF THE INVENTION

The present invention relates to a fastener system for multi-piece swagetype fasteners, methods of installation and a tool for installing suchfasteners.

The present invention relates to two-piece swage type fasteners orlockbolts generally of the type illustrated in U.S. Pat. Nos. 2,531,048and 2,531,049 to L. Muck both issued on Nov. 21, 1950, and in U.S. Pat.No. 3,915,053 to J. Ruhl, issued Oct. 28, 1975.

Swage type fasteners of the type noted are frequently of a two-piececonstruction comprising a pin and a collar adapted to be swaged intolocking grooves on the pin. The fasteners shown in the referenced '048and '049 patents are pull type swage fasteners while those shown in the'053 patent include both pull type and stump type versions of swagefasteners. In the typical pull type fastener, the pin is provided withan enlarged head and a pin shank having locking grooves in a lock grooveportion; the pin shank terminates in a pintail portion constructed withpull grooves adapted to be gripped by a jaw assembly of an installationtool. A swage anvil is provided on the tool to engage and swage thecollar into the locking grooves. A relative axial force is appliedbetween the pin and collar, and hence between workpieces to be fastenedtogether, as the tool pulls on the pin via the pintail portion with theforce being reacted by the engagement of the swage anvil with thecollar. This relative axial force pulls the workpieces together under aninitial clamp load.

As the relative axial load increases the swage anvil moves axially toradially overengage the collar, swaging it into the locking grooves,whereby the pin and collar are locked together and the final clamp loadon the workpieces is developed. The swage anvil has a swage cavity whichreceives the collar circumferentially for 360° and axially over themajority of the length of the collar or collar shank where a flangedcollar is employed whereby a substantial portion of the swageable collarmaterial is deformed into the locking grooves of the pin, generallyuniformly around its circumference.

The pintail portion is connected to the locking groove portion by abreakneck groove which is constructed to break at a preselected axialload after the swaging step has been completed whereby the pintailportion is severed and discarded.

In the stump type version, the lockbolt is set by a squeeze type toolwhich has a stationary member at one end of the workpieces for engagingthe pin head and a swage anvil at the opposite end for engaging thecollar. The fastener is set as the anvil moves axially against andradially over the collar with the axial force being reacted by theengagement of the stationary member with the pin head. Thus the stumptype fastener has the advantage of a shorter pin shank since the pintailportion with pull grooves and breakneck groove is not required. Becauseof the latter the stump version has the advantage of being lighter andof a lower cost.

But there are other advantages of the stump type swage fastener relativeto the pull type fastener. With the pull type fastener, the severedpintail portion creates debris in the work area requiring periodiccollection and disposal. Also the stump version will assure a smooth,finished end at the pin shank whereas the pull type pin shank willoccasionally have a rough surface from the break at the breakneckgroove. Finally the noise occasioned by pinbreak is absent in the stumptype fastener.

There are, however, numerous applications in which a stump type fastenercannot be used or it is not expedient to do so. One example is anassembly in which there is insufficient clearance on the pin head sideof the workpieces to permit access for the related stationary portion ofthe squeeze tool. Another example is an assembly having insufficientclearance to permit insertion of the longer pull type pin into themating openings of the workpieces. The present invention addresses suchproblems. Thus with the present invention a unique fastening systemincluding a swage type fastener and installation tool is provided for apull type installation but, as will be seen, having advantages of astump type fastener and installation. Indeed, where both squeeze typeand pull type applications and apparatus are present, the fastener ofthe present invention can be installed in either fashion resulting in areduction in overall inventory and in the numbers of different parts tobe stocked.

Thus the present invention is of a swage type fastener with a pin havinga shank constructed without a severable pintail portion but terminatingin a short, threaded or other gripable, pull portion of minimal length.A unique tool is shown which functions to provide a pull typeinstallation; the tool includes a threaded, hardened nut member adaptedto threadably engage the short pull portion via rotation by a rotarydrive motor. Once a sufficient number of threads have been engaged orgripped by the nut member, the pull tool is actuated to apply a relativeaxial force by pulling on the pin, through the nut member, with a swageanvil engaging the collar to react the pulling force. At this juncture,the fastening system performs similarly to a pull type installationsystem. Thus as the magnitude of the relative axial force increases theworkpieces being secured are pulled and clamped together under a desiredpreload. Upon further increases in the axial force the anvil will bemoved axially to radially overengage the collar and swage it radiallyinto the locking grooves on the pin shank providing the final clampload. Next the direction of relative axial force between the swage anviland nut member is reversed moving the swage anvil in the opposite axialdirection to thereby eject the swaged collar. Finally, the hardened nutmember is reverse rotated from the short, threaded pull portion removingthe installation tool and completing the installation. A rotary drivemotor in the pull tool is used to thread the nut member onto and offfrom the threaded pull portion. Thus no pintail portion is required tobe removed after swage and hence there is no related debris. In additionthe installation is quieter since pinbreak noise is eliminated. Thelength of pin shank comprising the short, threaded pull portion isminimal, i.e. around four threads, such that only a small difference inlength of pin shank remains relative to a comparable stump type pin setby a squeeze tool and/or the pin shank of a pull type fastener after thepintail portion has been removed by a conventional pull type tool.

In one form of the invention the lock grooves and threads of the pullportion of the pin are in the form of a continuous helical male thread.The collar is provided with a mating, female thread of a preselectedextent such that an initial clamp of the workpieces can be accommodated.However, the female collar thread is selected to be of a limitedcircumferential extent and shear strength such that, in response to therelative axial force and at a level prior to the initiation of collardeformation into the lock grooves of the pin, it will shear or deform;in this condition the collar will be generally free to move axially overthe pin and to respond to the installation loads in the same manner as acollar without such limited female thread form.

The preceding fastener structure with limited threaded collar issometimes referred to as a "fit-up fastener" and is shown and describedin the U.S. Patent application of R. Dixon for "Variable Clamp Fastenerand Method" No. 282,875, Filed Dec. 19, 1988 issued into U.S. Pat. No.4,867,625 on Sep. 19, 1989 and is incorporated herein by reference; thatstructure, however can be considered as prior art to the presentinvention. One advantage of the fit-up fastener structure in acombination in the present invention is that the workpieces can beinitially pulled together to remove gap thereby providing greatercertainty that a sufficient number of the threads of the pull portionwill extend beyond the collar and be accessible for gripping by the nutmember.

Alternatively, a collar with a flexible tab can be used for fit-up; sucha structure is shown in the U.S. Pat. No. 4,813,834 for "Fit-Up FastenerWith Flexible Tab-Like Structure and Method of Making Same" issued Mar.21, 1989 to Walter J. Smith.

In a preferred form of the invention, the tool nut member is designedsimply to threadably engage and thereby grip the minimum length pullportion of the pin; thus, in this first step, the tool nut member is notmoved against the collar with any significant force and hence is notused to pull the workpieces together and/or clamp them under an initialpreload. After the threaded engagement step, the installation tool isactuated to cause the swage anvil to move axially against the collar inresponse to a relative axial force applied between the nut member andthe anvil. Thus the initial clamp up and preload of the workpieces issubstantially provided for the first time by the relative axial forceapplied between the nut member as engaged with the pull portion of thepin shank and the engagement of the swage anvil with the collar. Aspreviously described, the relative axial force is increased until theswage cavity of the anvil is moved axially to radially overengage thecollar swaging the collar material into the pin. With this construction,the rotary drive motor for the nut member simply provides the functionof threading the nut member on and off the short pull portion of the pinshank and is not used to apply any significant axial load to theworkpieces. Thus the capacity of the drive motor can be small permittingthe overall size of the installation tool to be minimized. In one formof the invention, the engagement of the tool nut member on the threadedpull portion is limited and the nut member positioned thereon such thatthe collar, upon elongation in swage, will essentially not engage thenut member. Thus no significant axial bearing load will be appliedagainst the nut member from collar elongation after swage; this inhibitsincreases in friction between the engaged threads of the nut member andpull portion which would result from such bearing load. In this wayremoval torque can be maintained low which also facilitates the use of arotary motor of minimal size.

Prior crimp type fasteners, while utilizing a pintail-less or stump-likestructure would not provide the same advantages and/or ease ofinstallation as the present invention. For example, a threaded crimptype fastener would not provide the same flexibility and ease ofinstallation and would require more complex installation tools. In thisregard see the U.S. Pat. No. 3,421,562 to J. Orloff et al issued on Jan.14, 1969. There a threaded fastener nut or collar is first installed ona threaded pin shank and torqued to provide initial pull together andclamp up of the workpieces of a first magnitude; the final clamp load isachieved by crimping a smooth portion of the nut resulting in elongationof the nut and an increase in clamp load to a desired final magnitude.Thus in the system of the '562 patent the fastener is not set as eithera stump type or pull type as described and is unlike the system andfastener of the present invention. In this regard see also the U.S. Pat.No. 3,803,793 to W. Dahl issued on Apr. 16, 1974.

Another crimp type fastener is shown in the U.S. Pat. No. 4,012,828 toW. Dahl issued Mar. 22, 1977. There a threaded mandrel on a tool isfirst threaded onto a threaded pin shank until the mandrel engages asmooth bored collar to clamp the workpieces together and to apply aninitial preload of a first magnitude. Next crimping jaws, spacedradially about the collar, are actuated to move radially inwardly todeform the material of the collar into threads or locking grooves in thepin. The resultant collar elongation reacts between the engagedworkpiece and the engaged end of the threaded mandrel to provide anincreased clamp load of a final magnitude. After disengaging thecrimping jaws, the mandrel is threaded off the pin to complete theinstallation. Thus, again, in the system of the '828 patent, thefastener is not set as the stump or pull type fastener in the mannerpreviously described and also is unlike the system and fastener of thepresent invention. See also the U.S. Pat. No. 3,920,338 issued to W.Dahl on Nov. 18, 1975.

The U.S. Pat. No. 3,025,730 issued to H. Brilmyer et al on Mar. 20, 1962discloses the use of a manual installation tool on a swage fastenerhaving a threaded pintail portion and a breakneck groove with a nut onthe tool threadably engageable with the pintail portion. The system andfastener of the '730 patent is also unlike the system and fastener ofthe present invention.

The U.S. Pat. No. 4,299,519 issued to R. Corbett on Nov. 11, 1981discloses a fastener with a minimum length removable pintail portion; italso discloses a pin having an internally engageable pull groovestructure and no removable pintail portion. That fastener, however, doesnot disclose the externally, threaded short pull portion nor does itdisclose an internally threaded gripping portion.

As will be seen from the description of the embodiments which follows,various combinations of fastener pins and collars can be used with thesystem and installation tool of the present invention. Thus it is anobject of the present invention to provide a unique fastener systemincluding novel swage type fasteners having the advantages of a stumptype fastener and being installed generally as a pull type fastener.

It is another object of the present invention to provide a novelfastening system including a unique installation tool for use in settingswage type fasteners.

It is another general object to provide a unique fastening systemincluding a novel swage type fastener and a novel installation tool.

Other objects, features, and advantages of the present invention willbecome apparent from the subsequent description and the appended claims,taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an elevational view with some parts shown broken away andothers shown in section of a swage type fastener including a pin and acollar and embodying features of the present invention shown inrelationship to a portion of a tool of the present invention forinstalling the fastener with the tool not yet applied to the fastenerfor installing the fastener;

FIG. 2 is a view; to reduced scale, of the fastener and tool portion ofFIG. 1 shown after a nut member of the tool portion has been initiallythreadably applied to a threaded pull portion of the pin;

FIG. 3 is a view, to reduced scale, of the fastener and tool portion ofFIG. 1 shown after the collar has been swaged via a swage anvil intolocking grooves on the pin;

FIG. 4 is a view, to reduced scale, of the fastener and tool portion ofFIGS. 1-3 shown after the swage anvil of the tool portion has ejectedthe swaged collar but while the nut member of the tool portion is stillthreadably engaged with the pull portion of the pin;

FIG. 5 is an enlarged, fragmentary view of a portion of an installationtool, similar to that shown in FIGS. 1-4, but with the tool nut memberhaving a different thread configuration;

FIG. 6 is a view similar to FIG. 1 but depicting a modified swage typefastener having a pin of a different form including a threaded pullportion and a locking portion with annular locking grooves;

FIG. 7 is a view similar to FIG. 1 of a swage type fastener and portionof a tool but depicting a modified swage type fastener including acollar having a partial thread to provide initial fit-up of theworkpieces via engagement with a threaded pin;

FIG. 8 is a view, to reduced scale, of the fastener and tool portion ofFIG. 7 shown after a nut member of the tool portion has been initiallythreadably applied to a threaded pull portion of the pin;

FIG. 9 is a view, to reduced scale, of the fastener and tool portion ofFIG. 7 shown after the collar has been swaged into locking grooves onthe pin and initial swaging or snubbing of the collar has occurred;

FIG. 10 is a view, to reduced scale, of the fastener and tool portion ofFIGS. 7-9 shown after a swage anvil of the tool portion has ejected theswaged collar but while the nut member of the tool portion is stillthreadably engaged with the pull portion of the pin;

FIG. 11 is a fragmentary view to enlarged scale depicting a pin withdifferent thread forms for the pull groove portion and the lockinggroove portion of the pin;

FIG. 12 is a fragmentary view to enlarged scale depicting a pin withstill another combination of different thread forms for the pull grooveportion and locking groove portion of the pin;

FIG. 13a is a pictorial view with some parts shown broken away andothers shown in section of a modified swage fastener of a fit-up typeincluding a collar with a flexible tab for engagement with a threadedpin;

FIG. 13b is a pictorial view of the collar of FIG. 13a;

FIG. 14 is an elevational view of a swage type fastener having amodified pin structure where the locking groove and pull groove portionshave opposite hand threads and with the pull groove portion being of areduced diameter whereby a collar with a limited thread can be threadedonto the locking groove portion;

FIG. 15 is an elevational view similar to FIG. 14 but showing adifferent form of swage type fastener with the pin having opposite handthreads for the locking groove and pull groove portions but with suchportions being of a similar dimension and with the collar having aflexible tab such as depicted in FIG. 11;

FIG. 16 is an elevational view of a swage type fastener depicting thefastener with a threaded pin after it has been set with the pin beingdeformed by the swaged collar to have an hour glass configurationwhereby removal of the swaged collar by unthreading is resisted;

FIG. 17 is a fragmentary elevational view of a swage type fastener and aportion of an installation tool with the pin having an internal threadat its outer shank end and with the tool portion having a threadedmandrel adapted to engage the internal thread to apply thereby arelative axial force for setting the fastener;

FIG. 18 is a fragmentary elevational view of a swage type fastener andportion of an installation tool similar to that of FIG. 17 but with thepin having both internal and external gripping threads and with the toolportion having a mandrel and a nut for separate engagement of both theinternal and external threads for setting the fastener;

FIG. 19 is a drawing depicting the installation apparatus of the presentinvention and including a longitudinal sectional view of an installationtool for use with the controller system shown in FIG. 20;

FIG. 20 is a block diagram of a controller system including portions ofthe installation tool of FIG. 19 and embodying features of the presentinvention; and

FIG. 21 is a fragmentary view depicting a variation of the installationtool of FIG. 19.

Referring to FIGS. 1 through 4, there is shown a multi-piece fastener 10that includes a pin 12 and tubular collar 14. The pin 12 includes anenlarged head 16 and a pin shank 18 adapted to be received in alignedopenings 20 and 22 in a pair of workpieces 24 and 26, respectively. Thefastener 10 is a swage type fastener with the pin 12 being of a stumptype construction but which is adapted to provide installation as a pulltype fastener; alternatively the pin 12 facilitates installation of thefastener 10 as a stump type fastener. Thus the pin shank 18 isconstructed without a pintail portion and breakneck groove for severingsuch pintail portion. Pin shank 18 has a smooth shank portion 28adjacent the enlarged head 16 followed by a lock groove portion 30 (inbrackets) having locking grooves 32 and terminating in a short pullportion 34 (in brackets) having helical pull grooves 36. In theembodiment shown in FIGS. 1-4 the lock grooves 32 and pull grooves 36are defined by a uniform, continuous helical thread which can be of astandard thread form such as a UNC and/or UNF thread form. Collar 14 isof a cylindrical construction with an elongated collar shank 40terminating at one end in an enlarged flange 38. The collar 14 isadapted to be received upon the threaded lock groove portion 30 via asmooth through bore 42 of generally uniform diameter.

The fastener 10 can be used to join together workpieces 24 and 26 ofvarying combined thicknesses from a maximum thickness X to a minimumthickness X'. The length of the pin shank 18 is selected to be minimalto accommodate workpieces varying in such total thickness within thisgrip range. In order to accomplish this, the pull portion 34 ismaintained at a minimal length. Thus the pull portion 34 is of a short,limited length Y such that the excess length of pin shank 18 extendingbeyond the outer end of collar 14 will be Y for a maximum grip conditionX and a greater distance of Y' for a minimum grip condition X'. As willbe seen, the length Y of pull portion 34 is selected to provide asufficient number of threads to accept the pulling force to be appliedtherethrough to set the fastener 10 as a pull type fastener. In additionthe pin shank 18 can be provided with a slight excess length such thatthe pull portion 34 will be spaced from the outer end of the collar 14before and after swage for a purpose to be described.

FIGS. 1-4 show a portion of a tool 44 for installing the modified stumptype fastener 10 as a pull type fastener. The tool 44 comprises a rotarynut member 46 having internal gripping threads 48 sized to threadablyengage the helical pull grooves 36 of pull portion 34. The tool 44further includes an annular anvil member 50 having a swage cavity 52which receives the nut member 46; as will be seen, the anvil member 50is connected to an outer, anvil housing 54 adapted for axial movementrelative to the nut member 46. The swage cavity 52 of the anvil member50 is of a generally circular cross section of a diameter OD which issmaller than the circular outside diameter OD' of collar shank 40 suchthat as the anvil member 50 moves axially along and radially over collarshank 40, the collar material is swaged radially into the helicallocking grooves 32 on pin shank 18, thereby securing the pin 12 andcollar 14 to each other and securing the workpieces 24 and 26 under adesired clamp load. The swaging occurs generally over 360° of theengaged circumference of the collar shank 40 and generally over themajority of its length, i.e. preferably between around 75% and around90% of the length of collar shank 40.

FIG. 2 shows the tool 44 after nut member 46 has been threaded to apredetermined position onto the pull portion 34 of pin shank 18 toinitially grip the pin 12. Next, as shown in FIG. 3, the tool 44 isactuated to cause the anvil housing 54 to move axially forwardlyrelative to the nut member 46 and hence relative to the gripped pin 12.This action brings the swage anvil member 50 into engagement with theouter end of the collar shank 40 to apply a relative axial force betweenthe pin 12 and collar 14. As this force continues the workpieces areinitially clamped together under a desired preload. The relative axialforce increases moving the anvil swage cavity 52 axially to radiallyoverengage the collar shank 40 to swage the collar material radiallyinto the locking grooves 32 of the pin 12. After the swaging step hasbeen completed the relative axial force between the anvil housing 54 andthe nut member 46 is reversed whereby the swaged collar shank 40 isejected from the swage anvil 50 (see FIG. 4). The nut member 46 is nowreverse rotated to remove it from the pin pull portion 34 and theinstallation is complete; with workpieces 24 and 26 of maximum grip orcombined thickness X, the set fastener 10 will have a minimal excesslength Y of pin shank 18 extending beyond the outer end of the collarshank 40. Thus no pintail portion is required resulting in theadvantages previously noted.

In a preferred form of the invention, the pull portion 34 at maximumgrip X is located a minimal clearance distance of around one threadpitch P from the outer end of the collar shank 40 after initial clamp upand prior to swage (see FIGS. 1 and 2). This clearance P is selected toavoid engagement of the outer end of collar shank 40 with the nut member46 upon elongation of the shank 40 from swage whereby loading of theengaged threads between the nut member 46 and pull portion 34 is avoidedor negligible such that the removal torque required on the nut member 46can be kept low permitting the use of a small capacity rotary motorwhereby the overall size of tool 44 can be minimized.

The internal gripping threads 48 of the nut member 46 are of greaterstrength than the threaded pull grooves 36. Nut member 46 can be formedfrom a high strength alloy or case hardened material having a hard,wear-resistant surface on its internal gripping thread 48. In one formof the invention nut member 46 was formed of a ferrous material having aRockwell hardness of around 50 Rc.

In the form of the fastener 10 of FIGS. 1-4 the pin 12 can beconstructed of a ferrous material and have a Rockwell hardness of around33 to around 39 Rc for a grade 8 type fastener and a hardness of around25 to around 35 Rc for a grade 5 type fastener; however, in order toenhance the strength of the pull grooves 36 and hence minimize thenecessary overall length of pull portion 34, the pull portion 34 can behardened to a Rockwell hardness of at least around 5 Rc greater than thehardness of the remainder of the shank or preferably abound 15 Rcharder. In any event it is desirable that no more than around fourthreads or pull grooves 36 be required to sustain the relative axialpulling loads required to set the fastener. In this regard, it isdesirable that the number of pull grooves 36 be selected having a shearstrength no greater than around 30% and preferably 20% more than thatrequired to sustain the maximum load applied to the fastener 10 by thetool 44 to set the fastener 10 in a maximum grip condition. Thus thenumber of threads of the helical pull grooves 36 engaged is selected toprovide adequate strength to withstand the relative axial pulling loadto be subsequently applied in setting the fastener 10.

In the embodiment shown in FIGS. 1-4 the internal gripping threads 48 onnut member 46 and threaded pull grooves 36 can be of a generallyconventional, mating construction. However, it may be advantageous touse a somewhat modified thread on the nut member. Such a modifiedstructure is shown in FIG. 5 where components similar to like componentsin the embodiment of FIGS. 1 to 4 are given the same numeral designationwith the addition of the letter postscript "a" and unless describedotherwise are substantially identical with the like components of FIGS.1-4. Looking now to FIG. 5 the threads of the nut member are constructedto facilitate initial engagement. Thus the internal gripping threads 48aof nut member 46a have shoulders 55 which are of a width W which is lessthan the width W' of associated grooves 55' across the pitch line. Inone form of the invention the shoulder width W across the pitch line wasaround 75% of groove width W'. Also the crest diameter D of eachgripping thread shoulder 55 closely approaches the root diameter D' ofthe pull grooves 36a in order to maximize the effective shear are of thepull grooves 36a. Thus, the gripping threads 48a, utilizing the featuresnoted, are configured relative to the helical pull grooves 36a tofacilitate initial engagement onto the pull portion 34a without crossthreading or thread stripping and to enhance the effective shear areas.It will be seen, however, that various combinations of internal grippingthreads 48, 48a on nut member 46, 46a and pull grooves 36, 36a on pullportion 34, 34a can be advantageously utilized.

In some applications, it may be desirable that the locking grooveportion not be threaded and that the locking grooves be annular and nothelical. Such a construction is shown in the embodiment of FIG. 6 wherecomponents similar to like components in the embodiment of FIGS. 1 to 4are given the same numeral designation with the addition of the letterpostscript "b" and unless described otherwise are substantiallyidentical with the like components of FIGS. 1 to 4.

Thus looking now to FIG. 6, the pin 12b has its locking groove portion30b formed with locking grooves 32b which are annular, i.e. generallycircular and not helical, see '048 and '049 patents to L. Huck. Theremainder of the structure of fastener 10b is the same as fastener 10such that pull grooves 36b of pull portion 34b are defined by a helicalthread form whereby the installation of fastener 10b will be essentiallythe same as that for fastener 10.

As indicated, the fit-up fastener construction of the R. Dixonapplication could be used advantageously in the present invention toprovide initial pull together of the workpieces and hence to assist inproviding that the desired length of pin pull portion will be accessibleto the nut member. Such a construction is shown in FIGS. 7 to 10 wherecomponents similar to like components in the embodiment of FIGS. 1-4have been given the same numeral designation with the addition of theletter postscript "c" and unless described otherwise are substantiallyidentical with the like components of FIGS. 1 to 4.

Looking now to FIGS. 7 to 10, a fastener 10c is shown to include a pinmember 12c and tubular collar 14c. Pin member 12c has an elongated shank18c which extends with a clearance fit through aligned openings 20c and22c in a pair of workpieces 24c and 26c, respectively, to be securedtogether. An enlarged protruding head 16c at one end of pin shank 18cengages one side of workpiece 26c. A straight shank portion 28c extendsfrom pin head 16c and is followed by a lock groove portion 30c definedby a plurality of lock grooves 32c having a continuous, helical threadform. The outer end of the pin shank 18c terminates in a pull portion34c having a plurality of pull grooves 36c defined by a continuous,helical thread form.

The tubular collar 14c has a generally straight shank 40c terminating inan enlarged flange 38c. Both the pin head 16c and collar flange 38c canbe provided with wrenching flats to facilitate gripping by a wrench orother suitable tool for applying a relative torque between the pinmember 12c and collar 14c (see FIGS. 7 and 9). With regard to thelatter, the collar 14c has a generally smooth bore 42c of an internaldiameter to be in clearance with the pin shank 18c; a female thread 56is formed at the flange end of the bore 42c and is adapted tocomplementarily, threadably engage the helical locking grooves 32c. Fora reason to be seen the collar thread 56 is of a limited extent.

In operation, then, the workpieces 24c and 26c can be first joinedtogether by the threaded engagement between the limited collar thread 56and the threaded lock grooves 32c. The wrenching surfaces on the pinhead 16c and collar flange 38c facilitate torquing to a desiredmagnitude or extent of clamp. After this has been accomplished theinstallation tool 44c is applied to the fastener 10c and a relativeaxial force is applied between the pin 12c and collar 14c via the nutmember 46c threadably engaging the threaded pull grooves 36c of pullportion 34c and the swage anvil member 50c engaging the outer end of thecollar shank 40c. As the relative axial force increases, the limitedcollar thread 56 will shear or deform sufficiently to permit the shank40c of collar 14c to move further axially relative to the pin 12c. FIG.8 depicts the fastener 10c after the nut member 46c has been threadedonto the pull grooves 36c, the collar thread 56 has been deformed, andthe relative axial force has been increased to initially swage or snubthe collar 14c into the lock grooves 32c. In this condition, the pin 12cand collar 14c will now act in the same manner as pin 12 and collar 14in the embodiment of FIGS. 1-4. Thus the workpieces 24c and 26c areclamped together at a preselected preload by the relative axial forceinitially applied by the tool 44c between the pin 12c and collar 14c; asthe axial force increases, the collar shank 40c is swaged into thehelical locking grooves 32c completing the swaging operation (see FIG.10). Subsequently, upon further actuation of the tool 44c the swagedcollar shank 40c will be ejected from the anvil swage cavity 52c and thenut member 46c threaded off from the pull portion 34c thus completingthe installation.

Note that the contour of the swage cavity 52c of the anvil member 50cand the contour of the outer end of the collar shank 40c are such thatswaging of the collar shank 40c into the locking grooves 32c will notstart to occur at the lower magnitude of relative axial force requiredto shear or deform the limited collar thread 56 at the initiation of theswage step.

In one form of the invention, the helical locking grooves 32c are of ashallow construction and have a contour closely approximating astreamlined root configuration as shown in the Dixon application. Withthe fastener construction of FIGS. 7-10, it has been found that thedepth of the locking grooves 32c can be selected to provide a desiredminimum ratio of depth h to the crest diameter Du of the pin 12c. Themajor criteria of groove depth h is that it be sufficiently deep as apractical matter to receive and retain the material of the collar 14cafter swage. A groove depth h of around 0.04×Du or less is desirable,i.e. (h/Du)×10² =4. With such a shallow groove, the root diameter Drwill be maximized for a pin with a given crest diameter Du. This willprovide that a pin 12c of a given material will have nearly the maximumtensile strength available since tensile failure would generally occuracross the root diameter Dr which, when maximized, is only slightly lessthan the crest diameter Du. The maximized root diameter Dr will alsoprovide improved fatigue life.

With a shallow groove construction, it is desirable to provide thecollar shank 40c with a volume such that when swaged into the helicallocking grooves 32c it will have an excess volume over that required tofill the grooves 32c. In one embodiment, the volume of collar shank 40cwas selected to provide `overpacking` i.e., a volume of collar shank 40cto provide substantially more volume of collar material for fillinggrooves 32c than they could normally accept within the swage envelope ofthe swage cavity 52c of anvil member 56c and the confronting portion ofpin 12c. It has been found desirable to provide a volume of collarmaterial which has an excess of at least around 16%. The percentage`overfill` or `overpacking` noted can be generally determined in themanner described in the noted Dixon application.

Because of the shallowness of the locking grooves 32c, it is desirablethat the pin 12c be hard enough relative to the hardness of the collar14c to resist crushing or substantial yielding in tension or neckingdown from the high compressive swage loads. Thus, in one form of theinvention, the pin 12c could be made of AISI 4140 alloy steel or AISI1541 carbon steel having an ultimate shear strength of at least around95 KSI. The collar 14c could be made of AISI 1035 carbon steel having anultimate shear strength of at least around 45 KSI. Generally it isdesirable to utilize a pin 12c having an ultimate shear strengthrelative to that of collar 14c in the ratio in a range of around 1.8:1to around 2.4:1. Thus the pin 12c has a sufficient hardness to acceptboth the high tensile preloads desired and the swage loads on the collar14c substantially without yielding. The wall thickness of collar shank40c is selected to provide the necessary material to promote swaginginto the shallow helical locking grooves 32c and flow in elongation toprovide the desired clamp load. At the same time, the collar wallthickness at final swage is also selected to provide sufficient, radialstiffness or hoop strength to resist significant radial spring back fromthe locking grooves 32c both during initial swage and also undersubsequent tensile loading. Also, the volume of the collar 14c and swagecavity 52c are selected to provide movement of the material of collarshank 40c into the locking grooves 32c to assure a good fill. See thenoted Dixon application.

It is also desirable, that the widths of the groove portions 57 and pinshoulder portions 58 of locking grooves 32c and the complementary grooveportions 59 and shoulder portions 60 of the swaged collar 14c beproportioned in width relative to the respective shear strengths of thematerials of pin 12c and collar 14c such that both the pin shoulderportions 58 and the collar houlder portions 60, defined by interlockingmaterial of the swaged collar 14c, are in incipient or simultaneousfailure in shear at or above the preselected minimum ultimate designtensile load for the fastened joint of workpieces 24c and 26c (see FIGS.7 and 10). It is preferred that the design provide for the collarshoulder portions 60 to fail prior to the pin shoulder portions 58, i.e.the pin shoulder portions 58 would fail in shear at approximately 110%of the tensile load at which the collar shoulder portions 60 would fail.By proportioning the grooves as noted, the engaged length of pin andcollar can be minimized for a given tensile load. Of course, byproviding sufficient collar length, the above shear strengthrelationship can be maintained while providing for a tensile failurediametrically across the pin lock groove portion 30c.

Another advantage of employing proportioned strength as noted is thatthe shear strength of the limited collar thread 56 can now be maximizedpermitting the pre-fastened clamp via torquing to be at a relativelyhigh magnitude and/or permitting the fastener 10c in its pre-fastenedclamp condition to withstand the necessary loads to hold the structuretogether during a fit-up operation. This is achieved by virtue of thefact that the width of collar thread 56 is substantially the same as thewidth of the pin groove portions 57 of helical locking grooves 32c.

While the preceding relationships are taught in the noted Dixonapplication they can be of particular advantage in combination with thepresent invention. Thus, for example, in some instances the workpiecescould be pulled together removing the gap therebetween and assuring thata minimum length pin could be used.

In some applications it is desirable that the fastener be readilyremoved the same as a nut and a bolt. However, in a swage type fastenerwith a threaded pin the forces applied to the pin by the collar materialduring swage could result in distortion of the pin thread such thatremoval of the collar by unthreading would be severely hampered. Withthe fastener 10c, the pin 12c is constructed of a high strength materialrelative to the strength of the collar 14c and the lock grooves 32c areof the shallow form all as previously described; this results in littledistortion of the lock grooves 32c from the swaged collar 14c therebyfacilitating removal of the set fastener 10c by simply unthreading theswaged collar 14c from the pin 12c.

As previously noted, it is desirable that the nut member 46c be readily,threadably applied to the helical pull grooves 36c. In the embodiment ofFIG. 5 the internal gripping threads 48a of nut member 46a wereconfigured to facilitate initial engagement with the pull portion 34awhere the pull grooves 36a had a generally standard thread form. Butsuch initial engagement is also facilitated by a construction of pullgrooves where the crests or shoulders are of a lesser width than thewidth of the associated grooves. In the embodiment shown in FIGS. 7 to10, the helical pull grooves 36c are a continuation of and of the sameconstruction as the associated locking grooves 32c previously described.For purposes of ease of engagement it is believed that a ratio of thewidth of pin groove portions 57 of pull grooves 36c to the width of pinshoulder portions 58 of around 1.25:1 and greater may be desirable. Onthe other hand and as noted, a ratio of around 1.8:1 to around 2.4:1would be more desirable for the full advantage of proportioned strengthof the locking grooves 32c in the locking groove portion 30c. The lowerratio for the pull groove portion 34c is also desirable to provideincreased shear area and hence shear strength to resist the pull loads.Both can be accommodated by providing the locking grooves 32c to beconstructed to have the higher ratio for proportioned strength and thepull grooves 36c to have a lower ratio for increased shear strength toresist the pull load. This would also permit the use of fewer pullgrooves thereby facilitating the construction of a pull portion of aminimum length. Such a construction is shown in FIG. 11 where componentssimilar to like components in FIGS. 7 to 10 have been given the samenumeral designation with the addition of the letter postscript "d".

Looking now to FIG. 11, the pin 12d has a lock groove portion 30d withlocking grooves 32d and a pull portion 34d with pull grooves 36d. Thewidth Wg of the groove portions 57d of locking grooves 32d is greaterthan width Wg' of groove portions 57d' of pull grooves 36d. At the sametime the width Ws' of lock groove shoulder portions 58d is less than thewidth Ws' of pull groove shoulder portions 58d'. In this way the lockgroove portion 30d can be constructed to optimize the advantages ofproportioned strength while the pull portion 34d can be optimized toprovide ease of initial engagement by the nut member and adequate shearstrength over a minimal length to resist the applied pull loads. Notethat the thread pitch Pd can be maintained the same for both the threadson the lock groove portion 30d and on the pull portion 34d. In this casethe collar thread, such as thread 56 in FIG. 7, can be constructed toaccept the threads of both the lock groove portion 30d and the pullportion 36d. Note that in the construction shown in FIG. 11 the rootdiameter Drd is the same for both the threads of the lock groove portion30d and the pull portion 36d. By the use of a nut member constructedgenerally as shown in FIG. 5, the ease of initial engagement will befurther enhanced.

Another means of providing for a similar, balanced difference inthreaded groove constructions would be to make the root of the pullgrooves deeper thereby providing wider pull groove shoulders at theroot. Such a construction is shown in FIG. 12 where components similarto like components in the embodiment of FIG. 11 are given the samenumeral designation with the addition of the letter postscript "e".

Looking now to FIG. 12, the pin 12e has a lock groove portion 30e withlocking grooves 32e and a pull portion 34e with pull grooves 36e. Thegroove portions 57e' of pull grooves 36e are deeper than the grooveportions 57e of locking grooves 32e and hence have a root diameter Dre'smaller than locking groove root diameter Dre. Thus the width Wse oflock groove shoulder portions 58e is less than the width Wse' of pullgroove shoulder portions 58e'. In this way the lock groove portion 30ecan again be constructed to optimize the proportioned strengthadvantages while the pull portion 34e can be optimized to provideadequate shear strength over a minimal length to resist the applied pullloads. With a nut member constructed generally as shown in FIG. 5, theease of initial engagement will also be present. As with the priorembodiment, the thread pitch Pe can be maintained the same for boththread forms so as to accept the collar thread such as thread 56 ofFIGS. 7-10.

As noted another fit-up fastener construction could be used employingthe flexible tab-like structure of the Smith patent (supra); such aconstruction is shown in FIG. 13 where components similar to likecomponents in the embodiment of FIGS. 7 to 10 are given the samenumerical designation with the addition of the letter postscript "f" andunless described otherwise are substantially identical with the likecomponents of FIGS. 7 to 10.

Thus looking now to FIG. 13 fastener 10f is shown to include a pinmember 12f and tubular collar 14f. Pin member 12f has an elongated shank18f which extends through aligned openings 20f and 22f in a pair ofworkpieces 24f and 26f, respectively, to be secured together. Anenlarged protruding head 16f at one end of shank 18f engages one side ofworkpiece 26f. Adjacent the head 16f, the shank 18f has a straightportion 28f which is adapted to be received within aligned bores 20f and22f with a clearance fit. Following the straight portion 28f is a lockgroove portion 30f defined by locking grooves 32f in the form of acontinuous helical thread. The pin shank 18f terminates in a pullportion 34f defined by pull grooves 36f which are also in a helicalthread form and can be a continuation of the thread form of lock grooves32f.

The tubular collar 14f has a generally straight collar shank 40fterminating in an enlarged flange 38f. The collar 14f is provided with aflexible tab 56f located generally at the forward end of the collarshank 40f within smooth bore 42f.

In operation the pin 12f is located in the workpiece bores 20f and 22fand the collar 14f is located over the pin shank 18f. The flexible tab56f extends radially inwardly sufficiently to engage the ridges of thelock grooves 32f. The tab 56f, however, being flexible can deform orbend over the ridges of the lock grooves 32f until the collar flange 38fengages the workpiece 24f. The tapered or wedge like construction of theflexible tab 56f facilitates movement of the collar 14f onto the pin12f.

In some applications, it is advantageous to have the workpieces 24f and26f lightly clamped or even loosely held together to permit anappropriate fit-up of the associated structure prior to finalinstallation. After the pin 12f and collar 14f have been preassembled asnoted the installation tool (such as tool 44c), is applied in the mannerpreviously described, to the fastener 10f, by threading the nut member(such as 46c) onto the pull grooves 36f; next a relative axial force isapplied between the pin 12f and collar 14f via the nut member (such asnut member 46c) gripping the pull groove portion 34f and the swage anvil(such as 50f) engaging the outer end of the shank 40f of collar 14f. Asthe relative axial force increases the flexible tab 56f will deformsufficiently to permit the collar 14f to move further axially relativeto the pin 12f. The workpieces 24f and 26f can now be clamped togetherat a preselected preload by the relative axial force initially appliedbetween the pin 12f and collar 14f and, as the axial force increases,the collar 14f is swaged into the lock groove portion 30f. Subsequently,upon further actuation of the tool the swaged collar 14f will be ejectedfrom the anvil (such as 50f) and the nut member spun off thus completingthe installation.

Note that the contour of the swage cavity of the anvil (such as 50c) andthe contour of the outer end of the shank 40f of collar 14f are suchthat swaging of the collar 14f into the lock grooves 32f will not startto occur at the lower magnitude of relatively axial force required todeform, and in a sense to ratchet, the flexible tab 56f over the lockgrooves 32f during the pull up of the workpieces 24f and 26f at theinitiation of the swage operation.

Although a variety of materials would be suitable for the tab 56f, aflexible urethane of about a Shore A70 to around a Shore A90 hardnesswas found satisfactory. Another suitable material for tab 56f is anethylene copolymer such as ethylene vinyl acetate of about a Shore A70to around a Shore A90 hardness.

In some applications it may be desirable to provide the threads of thepull portion to be of a reverse hand to that of the lock groove portion.In this way, any tendency to turn the swaged collar threads off from thethreaded locking grooves on removal of the nut member of the tool wouldbe obviated. Such a construction is shown in FIG. 14 where componentssimilar to like components in the embodiment of FIGS. 7 to 10 are giventhe same numeral designation with the addition of the letter postscript"g" and unless described otherwise are substantially identical with thelike components of FIGS. 7 to 10.

Thus looking now to FIG. 14, the pin 12g of fastener 10g has a lockgroove portion 30g with the helical locking grooves 32g being in theform of a right hand thread. The pull portion 34g is provided with itshelical pull grooves 36g in the form of an opposite or left hand thread.Thus after the completion of the swage step, when the nut member of thetool (not shown) is oppositely rotated to disengage from the helicalpull grooves 36g on pull portion 34g the reaction on the pin 12g to theremoval torque will tend to torque the pin 12g relative to the collar14g to tighten the connection rather than loosen it. In the embodimentshown in FIG. 14, the pull portion 34g is of a reduced diameter relativeto the lock groove portion 30g such that the limited collar thread 56gcan be axially moved in clearance over the pull portion 34g and threadedonto the lock groove portion 30g. Where a non-threaded collar is usedthe pull portion 34g can be of the same diameter as the lock grooveportion. This is shown in FIG. 15 where components similar to likecomponents in the embodiment of FIG. 14 are given the same numeraldesignation with the addition of the letter postscript "h" and unlessdescribed otherwise are substantially identical with the like componentsof FIGS. 7 to 10 and 14.

Thus in FIG. 15 the pull portion 34h of pin 12h is of the same diameteras the lock groove portion 30h with the helical locking grooves 32hbeing of an opposite hand thread to the helical pull grooves 36h. Thelength of the pull portion 34h, however, is increased such that it willhave at least one thread 61 in line with the collar shank 40h; in thisway when the collar shank 40h is swaged onto the pin shank 18h some ofthe collar material will be swaged onto the opposite hand thread of thepull grooves 36h which will provide an anti-rotation feature resistingloosening from vibration. Note also that the combination of oppositehand threads will provide a substantially tamper proof joint. Note thata collar, such as collar 14f having a flexible tab 56f, could be used toprovide the fit-up function regardless of the use of the combination ofright and left hand threads of same diameter on pin shank 18h.

Another tamper proof construction is shown in FIG. 16 where componentssimilar to like components in the embodiment of FIGS. 1 to 4 have beengiven the same numeral designation with the addition of the letterpostscript "i" and unless described otherwise are substantiallyidentical with the like components of FIGS. 1 to 4.

Looking now to FIG. 16 the lock groove portion 30i of pin 12i offastener 10i can be formed with standard UNC or UNF threads and can bemade of a material which is somewhat soft relative to the material ofthe collar 14i. Thus upon swaging the collar shank 40i into the lockgroove portion 30i, the lock groove portion 30i will neck locally suchthat the diameter Dch in the center is less than the diameter Deh atopposite ends; this defines an "hourglass" or concave configurationwhich resists unthreading of the swaged collar 14i from the pin 12i.Such a construction can be provided where the pin 12i had a standardthread form and was of a ferrous material having a hardness of around 35Rc and the collar 14i was of a ferrous material having a hardness ofaround 75 Rb. This relationship would differ for different thread formssuch as the shallow lock grooves herein described. Localized necking hasoccurred in swage type fasteners with annular grooves but is generallyavoided with threaded grooves where removability by unthreading isdesired. The hour glass construction resists rotation and unthreading ofthe swaged collar 14i from the pin 12i such that the set fastenerprovides a tamper proof construction. The degree of concavity need notbe extreme but in some cases will provide sufficient resistance toremoval by torquing where the center diameter Dch has been reduced by atleast around 2% relative to the end diameter Deh. Note that the threadedpull portion 34i could be hardened, as previously noted, to increase thestrength of the helical pull grooves 36i.

It is desirable that the pull portion be maintained as short aspossible; yet the minimum length of the pull portion is dictated by theminimum number of pull grooves required to provide sufficient shearstrength to withstand the pulling loads to set the fastener. In someconstructions the pull portion can be defined by internal threads at theend of the pin shank adapted to be gripped by a threaded male mandrel.Such a construction is shown in FIG. 17 where components similar to likecomponents in the embodiment of FIGS. 1 to 4 have been given the samenumeral designation with the addition of the letter postscript "j". Thuslooking now to FIG. 17, the pin 12j of fastener 10j has a lock grooveportion 30j extending generally over the outer end of the pin shank 18j.The outer end of pin shank 18j is formed with an axial bore 64 definingthe pull portion 34j; the bore 64 is provided with internal, femalehelical pull grooves 36j. The tool 44j has an axially extending threadedmale, mandrel 66 adapted to threadably engage the internal pull grooves36j whereby the relative axial force can be applied between internalpull grooves 36j and the swage anvil member 50j to set the fastener 10jin the manner as described before. Thus with this construction theoverall length of the pin shank 18j can be minimized.

In another form of the invention the pull portion of the pin can bedefined by a combination of external and internal threads. Such aconstruction is shown in FIG. 18, where components similar to likecomponents in the embodiments of FIGS. 1-4 and 17 are given the samenumeral designation with the addition of the letter postscript "k". Thuslooking now to FIG. 18, the fastener 10k has pin 12k a lock grooveportion 30k terminating in a limited pull portion 34k having externalhelical pull grooves 36k and internal helical pull grooves 36k' in anaxial bore 64k. The tool 44k in addition to having nut member 46k whichwill engage the external, helical pull grooves 36k is provided with anaxially extending threaded male, mandrel 66k adapted to engage theinternal pull grooves 36k'. The mandrel 66k is separate from the nutmember 46k so that each are threaded separately onto the mating internalpull grooves 36k' and external pull grooves 36k, respectively. Thecombination of internal and external pull grooves will also permit theuse of a pull portion 34k of minimal length resulting in pin shank 18kbeing minimal in length.

The tool 44 also represents a unique element of the fastening system ofthe present invention and is shown in greater detail in FIG. 19. FIG. 19illustrates structural features of the tool 44 operating in accordancewith the sequence shown in FIGS. I through 4 and is shown in combinationwith a control system 67 shown in FIG. 20 to be described.

Thus looking to FIGS. 19 and 20 and FIGS. 1-4, the tool 44 has a sensingrod 68 which extends axially through nut member 46 to detect the extentthat the nut member 46 has been moved onto the pull portion 34 of pinshank 18. As the nut member 46 is rotated by a reversible air motor 70it advances axially on the pull portion 34 until sensing rod 68 contactsthe end surface of pin shank 18 and is moved axially rearwardly relativeto nut member 46. The rearward movement of sensing rod 68 and/or a timeris used to determine actuation of a source of compressed air 71 for themotor 70 that rotates nut member 46. The movement of sensing rod 68 mayalso be used to determine actuation of a fluid power source 69 to moveanvil member 50 axially relative to nut member 46 such that it willfirst engage the outer end of the collar shank 40 to apply an initialpreload to the workpieces 24 and 26 and then upon continued actuationwill move axially to radially overengage the collar 14 swaging it intolocking grooves 32 on the pin shank 18.

The tool 44 includes an elongated annular housing assembly 72 having acentral, longitudinal axis 74. The housing assembly 72 has a cylinderhousing 76 internally contoured to form a fluid cylinder cavity 78. Apiston 80 is disposed within cylinder housing 76 for reciprocatingmovement in the cylinder cavity 78 in response to selective introductionof hydraulic fluid through ports 84 and/or 86 in the cylinder housing76. Cylinder housing 76 is threadably connected to outer anvil housing54 via a threaded connection 88 and hence is connected to swage anvilmember 50 whereby the piston 80 will move axially relative to the anvilmember 50 as shown in FIGS. 1 through 4 to swage collar 14 onto pin 12.Swage anvil member 50 is also threadably connected to the forward end ofouter anvil housing 54 via a threaded connection 90. Housing assembly 72also includes rear housing member 92 which is affixed to the cylinderhousing 76 via a ring of bolts 94.

The nut member 46 is rotatably mounted within the swage cavity 52 ofanvil member 50. Nut member 46 is rotatably driven around the tool axis74 by the reversible air motor 70. The drive system includes a firstbevel gear 96, a second bevel gear 98, and an elongated drive shaft 100.Shaft 100 extends axially through piston 80 but can rotate relativethereto to impart the rotary drive force to nut member 46.

Fluid piston 80 includes a piston head 102 and a piston rod 104 with thepiston head 102 dividing the fluid cylinder cavity 78 into forward andrearward chambers 106 and 108, respectively. A tubular extension 110extends rearwardly from piston head 102 through a bore 112 in the endwall 114 of cylinder housing 76. Introduction of pressurized hydraulicfluid through port 84 into the forward cylinder chamber 106 causes ahydraulic force to be exerted on the forward or rod end of piston 80 todrive the piston 80 axially rearwardly relative to housing assembly 72.Introduction of pressurized fluid through port 86 into the rearwardcylinder chamber 108 causes a hydraulic force to be applied to therearward or head end of piston 80 causing it to move axially forwardly,i.e. to the position shown in FIGS. 1 and 19.

Air motor 70 is attached to rear housing member 92 in a radialorientation such that the motor rotational axis 116 extends radially ortransversely from central housing axis 74. A motor shaft 118 carries thefirst bevel gear 96 that meshes with the second bevel gear 98 supportedin anti-friction bearings 120 for rotation around central housing axis74 while anti-friction bearings 121 support the first bevel gear 96 forrotation around its axis 116. Drive shaft 100 is splined with grooves122 to mate with ball splines 124 on second bevel gear 98, such thatgear 98 can transmit a rotary drive force to drive shaft 100 and thedrive shaft 100 can move axially relatively thereto along centralhousing axis 74.

Drive shaft 100 extends forwardly from second gear 98 through piston 80.The extreme forward end of drive shaft 100 is configured as a squarecross-sectioned male drive element 126 seatable within a similarlysectioned socket 128 formed in the confronting end face of nut member46. The outer side surfaces of nut member 46 are cylindrical surfacesslidably and rotatably mounted within the swage cavity 50 of swage anvil36. An annular sleeve 130 carried by the piston rod 104 blocks nutmember 46 from axial motion while permitting the nut member 46 to rotaterelatively thereto around central housing axis 74.

The elongated, non-rotary position sensing rod 68 extends through nutmember 46 and elongated drive shaft 100. The rearward end of sensing rod68 is attached to a disk 132 that is located within an annular ringstructure 134 of a stepped construction and which is axially slidablewithin rear housing member 92. A coil spring 136 within nut member 46biases sensing rod 68 rearwardly to the position shown in FIGS. 1 and19.

During rotary motion of nut member 46 onto pin pull portion 34 (FIG. 2)and in response to its axial movement onto the pin shank 18, sensing rod68 engages the end face of the pin shank 18. The rod 38 is thus movedrearwardly (as in FIG. 2) so that disk 132 moves rearwardly a slightdistance. This slight movement permits a light spring 138 to slide ringstructure 134 rearwardly in a manner to sequentially operate twoelectric position sensing switches 140 and 142. The second switch 142 islocated a very slight distance to the rear of the first switch 140 suchthat first switch 140 is actuated before second switch 142. For example,the first position switch 140 would be actuated when nut member 46 wasonly partially threaded onto the threads of pull portion 34, i.e. onlytwo threads instead of the desired four threads; on the other hand thesecond position switch 142 would be actuated only after the nut member46 had been fully threaded the desired amount onto the threads of thepull portion 34, i.e. four threads.

Thus the actuation point for second switch 142 is predetermined and canbe selected so that nut member 46 will be threaded a known distance ontothe threads of pull portion 34 such that a sufficient number of threadson the pull portion 34 are engaged to fully accept the reaction loadsfor the swaging of the collar 14 into the lock groove portion 30.

Position switches 140, 142 are incorporated into the controller system67 which includes a programmable controller 144; the programmablecontroller 144 includes a manually actuable trigger switch 146 actuableby the operator for initiating the installation cycle by energizingmotor 70 via air supply 71 and starting a timer 148. Assuming that thesecond position switch 142 is actuated within the time period allowed bythe timer 148, i.e. approximately one or two seconds, the programmablecontroller 144 will signal the air supply 71 to de-energize motor 70 andthen energize a solenoid valve 150 controlling flow of hydraulic fluidfrom the fluid pressure supply 69 to port 84 (FIG. 19). With motor 70and nut member 46 motionless, the hydraulic fluid will act on the rodend of piston 80 to effectively move the tool housing assembly 72forwardly, thereby moving anvil 36 forwardly relative to nut member 46to perform the swaging operation on collar 14. In this mode the highpressure output line from fluid source 69 will be connected to thesolenoid valve 150 via control valve 151.

As the anvil 36 reaches the end of the swage stroke it generates highback pressure on the fluid in the line leading to port 84. The high backpressure operates a second fluid pressure switch 154 to signal theprogrammable controller 144 to actuate the solenoid valve 150 to itsoriginal condition relative to ports 84 and 86. Port 84 is thusconnected to a drain or return line, while port 86 is connected to thehigh pressure side of the fluid pressure source 69 until return and thenheld there under a low idle pressure. Accordingly, housing assembly 72is returned rearwardly to its FIG. 2 position ejecting the swaged collar14 from the swage cavity 52 of anvil 50. A second fluid pressure switch154 in the line leading to port 86 responds to back pressure to signalthe programmable controller 144 to energize motor 70 via the air source71 in the reverse direction, whereby nut member 46 is spun off of thethreads on pull portion 34 to approximate the condition shown in FIG. 1.

First position switch 140 is in the nature of a safety switch to enablethe programmable controller 144 to provide a second chance at achievinga collar swage action if nut member 46 is initially threaded aninsufficient distance onto pin pull portion 34. In this case, if thetimer 148 times out and first position switch 140 is actuated but secondposition switch 142 is not actuated this signifies a minimal butinsufficient threading of nut member 46 onto pull portion 34. The timeperiod for the first actuation of first switch 140 is around 5 to 10second. If switch 140 is not actuated in that time period the controller144 will abort the cycle and bring the system 67 back to its originalstate requiring another actuation of the trigger switch 144. Thus inresponse to these signals from switches 140 and 142 and timer 148 theprogrammable controller 144 actuates the solenoid valve 150 to providehydraulic fluid at a predetermined low, holding pressure to port 84.This holding pressure will be less than the full pressure for swage butof a sufficient, low magnitude only to move swage anvil 50 against theend of collar shank 40 to take up the gap between workpieces 24 and 26.In this regard the first fluid pressure switch 152 senses the magnitudeof pressure to port 84 and will generate a signal when the low holdingpressure is attained; in response the controller 144 will interrupt thecycle and return the piston 80 to its return position. Thus when the gapis taken up, the programmable controller 144 will have returned thepiston 80 to its original position and will again initiate the timer 148to give motor 70 a second chance to thread nut member 46 the requireddistance onto pull portion 34. If second position switch 142 is nowactuated on the second attempt, then the swaging operation will becarried out in the desired fashion as previously described. If thesecond switch 142 is not actuated on the second attempt, theprogrammable controller 144 will return the controller system 67 to itsreturn condition, reversing the pressure at ports 84 and 86 andactuating the air supply 71 to unthread the nut member 46 from the pullportion 34.

Thus the controller system 67 is designed so that the swaging operationwill not be attempted until after second position switch 142 has beenactuated, i.e., until the system is assured that nut member 46 has beenthreaded a sufficient distance onto pull portion 34 to adequately resistthe axial loads imposed by the swaging operation.

In a similar manner controller system 67 will not initiate the actuationof the pull up of the workpieces via the low holding pressure if firstposition switch 140 is not actuated within a time prescribed by timer148, i.e. less than around two threads engaged. Again the nut member 46will be unthreaded from pull portion 34 without the application of fluidpressure and without application of a relative axial pulling force tothe fastener 10.

In the system of FIGS. 19 and 20 a reversible air motor 70 of a typeModel No. MMR-0002X by Micro Motors, Inc. of Santa Ana, Calif., U.S.A.was utilized; at the same time a programmable controller 144 of a typeproduced by DeVilbiss U.S.A. was used and can be programmed to providethe noted sequence of operation by one skilled in the art.

FIG. 21 illustrates the operation of another tool embodying theinvention. In the embodiment of FIG. 21 components similar to likecomponents in the embodiment of FIGS. 1 through 4 and 19 are given thesame numeral designation with the addition of the letter postscript "m"and unless described otherwise are substantially identical with the likecomponents of FIGS. 1 to 4 and 19. In this case there is no positionsensing rod 68. Instead, nut member 46 m of tool 44 m is rotated untilthe end face 156 of the nut member cavity 158 abuts against the endsurface of pin shank 18 m. When this occurs a back pressure is developedat a reversible air motor (such as motor 70) used to rotate nut member46 m. Such a back pressure can be sensed by the controller system (suchas system 67) and upon attainment of a known magnitude can generate asignal to stop the air motor. After nut member 46 m stops rotating, theswage anvil member 50 m is driven axially and radially over the collar14 m to swage the collar material into the threads of lock grooveportion 30 m on pin shank 18 m. Thus the operation of the tool 44 m isgenerally similar to that of the tool 44 in FIG. 19, one differencebeing that the magnitude of air pressure on the motor (such as 70) issensed instead of nut position on the pin via a sensing rod 68 and suchpressure signal is used to halt rotation of nut member 46 m. In thiscase, however, the repeatability factor noted with the embodiment ofFIG. 19 will not be present.

It should be noted that other groove forms could be used for the lockinggrooves and pull grooves. For example the pull grooves could be in theform of a multiple thread; with a mating thread on the nut member thefull engagement could occur with fewer turns of the nut member.

Also the pull portion of the pin could be color coded so as to provide avisual indication to the operator that the tool nut member has engaged asufficient number of pull grooves and/or that the pull groove portionextends the desired distance beyond the end of the collar shank.

While it will be apparent that the preferred embodiments of theinvention disclosed is/are well calculated to fulfill the objects abovestated, it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the properscope or fair meaning of the invention.

What is claimed is:
 1. In a fastening system for securing a plurality ofworkpieces with a multi-piece swage type fastener through alignedopenings in the workpieces, the method comprising:a. providing a pinmember with an elongated pin shank and an enlarged head, b. providingsaid pin member with a locking groove portion on said pin shankcomprising a plurality of generally circumferentially extending lockinggrooves, c. locating said pin member with said pin shank extendingthrough the aligned openings, d. providing said pin member with a pullportion comprising a plurality of generally circumferentially extendingpull grooves, e. said pull portion located at the terminal end of saidpin shank with said pull grooves defining a thread form, f. providing atubular collar and locating said collar on said pin shank surroundingsaid locking grooves with said pull grooves being accessible at an outerend of said collar, g. providing a gripping member adapted to threadablyengage and grip said pull grooves, h. providing a swage anviloperatively associated with said gripping member and adapted to engagesaid collar and to radially overengage said collar to swage it into saidlocking grooves in response to a relative axial force of a firstmagnitude, i. threadably engaging said pull grooves with said grippingmember, j. automatically detecting the extent of relative engagement ofsaid pull grooves by said gripping member, thereby determining a firstextent or a second extent of relative engagement, with said first extentbeing greater than said second extent, k. if said first extent is sensedthen automatically applying a relative axial force between said grippingmember and said swage anvil of a first magnitude, thereby swaging saidcollar into said locking grooves and clamping the workpieces togethervia said pin and said collar under a final clamp load, and then removingsaid swage anvil from said collar and unthreading said gripping memberfrom said pull portion with said pull portion remaining integral withsaid pin, l. if said first extent is not sensed but said second extentis sensed then automatically applying a relative axial force of a secondmagnitude between said gripping member and said swage anvil, therebypulling the workpieces together under an initial clamp load, said secondmagnitude being less than said first magnitude and less than that atwhich initiation of swaging of said collar into said lock grooves ofsaid pin occurs, and after application of the relative axial force ofsaid second magnitude applying a rotary force, thereby threading saidgripping member further onto said pull groove portion until said firstextent is attained and then repeating step k.
 2. In a fastening systemfor securing a plurality of workpieces with a multi-piece swage typefastener through aligned openings in the workpieces, the methodcomprising:a. providing a pin member with an elongated pin shank and anenlarged head, b. providing said pin member with a locking grooveportion on said pin shank comprising a plurality of generallycircumferentially extending locking grooves, c. locating said pin memberwith said pin shank extending through the aligned openings, d. providingsaid pin member with a pull portion comprising a plurality of generallycircumferentially extending pull grooves, e. said pull portion locatedat the terminal end of said pin shank with said pull grooves defining athread form, f. providing a tubular collar and locating said collar onsaid pin shank surrounding said locking grooves with said pull groovesbeing accessible at an outer end of said collar, g. providing a grippingmember adapted to threadably engage and grip said pull grooves, h.providing a swage anvil operatively associated with said gripping memberand adapted to engage said collar and to radially overengage said collarto swage it into said locking grooves in response to a relative axialforce of a first magnitude, i. threadably engaging said pull grooveswith said gripping member, j. automatically detecting the extent ofrelative engagement of said pull grooves by said gripping member,thereby determining a first extent of relative engagement, k. if saidfirst extent is equal to a predetermined value, then automaticallyapplying a relative axial force between said gripping member and saidswage anvil of a first magnitude, thereby swaging said collar into saidlocking grooves and clamping the workpieces together via said pin andsaid collar under a final clamp load, and after swaging of the collarremoving said swage anvil from said collar and unthreading said grippingmember from said pull portion, l. if said first extent is less than saidpredetermined value then automatically inhibiting application of therelative axial force of said first magnitude.
 3. In a fastening systemfor securing a plurality of workpieces with a multi-piece swage typefastener through aligned openings in the workpieces, the methodcomprising:a. providing a pin member with an enlarged head and anelongated pin shank, b. providing said pin member with a locking grooveportion on said pin shank comprising a plurality of generallycircumferentially extending locking grooves, c. locating said pin memberwith said pin shank extending through the aligned openings, d. providingsaid pin member with a pull portion comprising a plurality of generallycircumferentially extending pull grooves, e. said pull portion locatedat the terminal end of said pin shank with said pull grooves defining athread form, f. providing a tubular collar and locating said collar onsaid pin shank surrounding said locking grooves with said pull groovesbeing accessible at an outer end of said collar, g. providing a grippingmember adapted to threadably engage and grip said pull grooves, h.providing a swage anvil operatively associated with said gripping memberand adapted to engage said collar and to radially overengage said collarto swage it into said locking grooves in response to a relative axialforce of a first magnitude, i. threadably engaging said pull grooveswith said gripping member, j. automatically detecting the extent ofrelative engagement of said pull grooves by said gripping member,thereby determining extent of relative engagement, k. if relativeengagement no greater than said preselected extent is sensed thenpreventing the application of relative axial force of the firstmagnitude, l. if said preselected extent is sensed and the relativeaxial force of first magnitude has not been applied, then applying arelative axial force of a second magnitude between said gripping memberand said swage anvil to pull the workpieces together under an initialclamp load, eaid second magnitude being less than said first magnitudeand less than that at which initiation of swaging of said collar intosaid lock grooves of said pin occurs, m. after application of therelative axial force of said second magnitude applying a rotary forcefor threading said gripping member further onto said pull groove portionwhile inhibiting application of the relative axial force of firstmagnitude, n. after said gripping member has been threaded further ontosaid pull portion applying a relative axial force between said grippingmember and said swage anvil of said first magnitude, thereby swagingsaid collar into said locking grooves.
 4. In a fastening system forsecuring a plurality of workpieces with a multi-piece swage typefastener with the workpieces including an inner workpiece and at leastone outer workpiece,the fastener comprising a pin member and a tubularcollar and adapted to be set by a relative axial force therebetween, thepin member having an elongated pin shank with a locking groove portionon the pin shank, means operatively connecting the pin shank in loadbearing relationship with the inner workpiece and with the pin shankadapted to extend through an aligned opening in the outer workpiece, thepin shank having a pull portion comprising a plurality of generallycircumferentially extending pull grooves, the pull portion located atthe terminal end of the pin shank with the pull grooves defined by athread form, the tubular collar adapted to be located on the pin shanksurrounding the locking grooves with the pull grooves being accessibleat an outer end of the collar, the method of setting the fastenercomprising:progressively threadably engaging the pull grooves generallyone a a time by a gripping member, engaging the collar by a swage anvilas the pull grooves are threadably engaged by the gripping member, andin a first installation step applying a relative axial force of a firstmagnitude between the pin member and the collar by the gripping memberand the swage anvil hereby swaging the collar into the locking groovesor alternatively and in a second installation step and prior to applyingthe relative axial force of the first magnitude applying a relativeaxial force of a second magnitude being less than the first magnitude topull the workpieces together, automatically detecting the extent ofrelative threaded engagement between the pull grooves and the grippingmember as the gripping member is threadably engaging the pull grooves,automatically preventing the application of the relative axial force ofthe second magnitude for the second installation step unless apreselected minimum extent of the final relative threaded engagement ofthe pull grooves by the gripping member is automatically detected and atthe same time preventing the application of relative axial force offirst magnitude for the first installation step, and for the secondinstallation step automatically applying the relative axial force of thesecond magnitude if the preselected minimum extent of the final relativethread engagement is detected.
 5. The fastening system of claim 4 withthe method of setting the fastener further comprising:automaticallyunthreading the gripping member from the pull grooves if the preselectedminimum extent of threaded engagement has not been attained by thegripping member within a predetermined time period.
 6. In a fasteningsystem for securing a plurality of workpieces with a multi-piece swagetype fastener with the workpieces including an inner workpiece and atleast one outer workpiece,the fastener comprising a pin member and atubular collar and adapted to be set by a relative axial forcetherebetween, the pin member having an elongated pin shank with alocking groove portion on the pin shank, means operatively connectingthe pin shank in load bearing relationship with the inner workpiece andwith the pin shank adapted to extend through an aligned opening in theouter workpiece, the pin shank having a pull portion comprising aplurality of generally circumferentially extending pull grooves, thepull portion located at the terminal end of the pin shank with the pullgrooves defined by a thread form, the tubular collar adapted to belocated on the pin shank surrounding the locking grooves with the pullgrooves being accessible at an outer end of the collar, the method ofsetting the fastener comprising:progressively threadably engaging thepull grooves generally one at a time by a gripping member, automaticallydetecting the extent of relative threaded engagement between the pullgroove and the gripping member as the gripping member is threadablyengaging the pull grooves, engaging the collar by a swage anvil as thepull grooves are threadably engaged by the gripping member, the swageanvil adapted to engage the collar thereby swaging it into the lockinggrooves in response to a relative axial force of a first magnitudeapplied between the pin member and the collar by the gripping member andthe swage anvil, automatically preventing the application of therelative axial force of the first magnitude unless a predeterminedmaximum extent of relative threaded engagement of the pull grooves bythe gripping member is automatically detected, and automaticallyapplying the relative axial force of the first magnitude if thepredetermined maximum extent of relative threaded engagement isdetected.
 7. The fastening system of claim 6 with the method of settingthe fastener further comprising:automatically halting the step ofprogressively engaging the pull grooves and automatically preventing theapplication of the relative axial force of the first magnitude unlessthe preselected maximum extent of threaded engagement has been detectedwithin a predetermined time period.
 8. In a fastening system or securinga plurality of workpieces with a multi-piece swage type fastener withthe workpieces including an inner workpiece and at least one outerworkpiece,the fastener comprising a pin member and a tubular collar andadapted to be set by a relative axial force therebetween, the pin memberhaving an elongated pin shank with a locking groove portion on the pinshank, means operatively connecting the pin shank in load bearingrelationship with the inner workpiece and with the pin shank adapted toextend through an aligned opening in the outer workplace, the pin shankhaving a pull portion comprising a plurality of generallycircumferentially extending pull grooves, the pull portion located atthe terminal end of the pin shank with the pull grooves defined by athread form, the tubular collar adapted to be located on the pin shanksurrounding the locking grooves with the pull grooves being accessibleat an outer end of the collar, the method of setting the fastenercomprising:progressively threadably engaging the pull grooves generallyone at a time by a gripping member, automatically detecting the extentof relative threaded engagement between the pull grooves an the grippingmember as the gripping member is threadably engaging the pull grooves,engaging the collar by a swage anvil as the pull grooves are threadablyengaged by the gripping member, the swage anvil adapted to engage thecollar thereby swaging it into the locking grooves in response to arelative axial force of a first magnitude applied between the pin memberand the collar by the gripping member and the swage anvil oralternatively and prior to applying the relative axial force of thefirst magnitude applying a relative axial force of a second magnitudebeing less than the first magnitude to pull the workpieces together,after a preselected maximum extent of relative threaded engagement ofthe pull grooves by the gripping member has been automatically detectedapplying a relative axial force of the first magnitude, thereby swagingthe collar into the locking groove, automatically preventing theapplication of the relative axial force of the first magnitude unlessthe preselected maximum extent of relative threaded engagement of thepull grooves by the gripping member has been automatically detected,automatically preventing the application of the relative axial force ofthe second magnitude unless a preselected minimum extent of finalrelative threaded engagement of the pull grooves by the gripping memberis automatically detected with said preselected minimum extent beingless than said preselected maximum extent.
 9. The fastening system ofclaim 8 with the method of setting the fastener furthercomprising:automatically unthreading the gripping member from the pullgrooves if the preselected minimum extent of threaded engagement has notbeen attained by the gripping member within a predetermined time period.10. The fastening system of claim 8 with the method of setting thefastener further comprising:automatically halting the step ofprogressively engaging the pull grooves and automatically preventing theapplication of the relative axial force of the first magnitude unlessthe preselected maximum extent of threaded engagement has been detectedwithin a predetermined time period.
 11. The fastening system of claim 8with the method of setting the fastener further comprising:automaticallyunthreading the gripping member from the pull grooves if the preselectedminimum extent of threaded engagement has not been attained by thegripping member within a predetermined time period, automaticallyhalting the step of progressively engaging the pull grooves andautomatically preventing the application of the relative axial force ofthe first magnitude unless the preselected maximum extent of threadedengagement has been detected within a predetermined time period.
 12. Ina fastening system for securing a plurality of workpieces with amulti-piece swage type fastener with the workpieces including an innerworkpiece and at least one outer workpiece,the fastener comprising a pinmember and a tubular collar and adapted to be set by a relative axialforce therebetween, the pin member having an elongated pin shank with alocking groove portion on the pin shank, means operatively connectingthe pin shank in load bearing relationship with the inner workpiece andwith the pin shank adapted to extend through an aligned opening in theouter workpiece, the pin shank having a pull portion comprising aplurality of generally circumferentially extending pull grooves, thepull portion located at the terminal end of the pin shank with the pullgrooves defined by a thread form, the tubular collar adapted to belocated on the pin shank surrounding the locking grooves with the pullgrooves being accessible at an outer end of the collar, the method ofsetting the fastener comprising:progressively threadably engaging thepull grooves generally one at a time by a gripping member, engaging thecollar by a swage anvil as the pull grooves are threadably engaged bythe gripping member, the swage anvil adapted to engage the collar andswage it into the locking grooves in response to a relative axial forceof a first magnitude applied between the pin member and the collar bythe gripping member and the swage anvil or alternatively and prior toapplying the relative axial force of the first magnitude applying arelative axial force of a second magnitude being less than the firstmagnitude to pull the workpieces together, automatically detecting theextent of relative engagement of the pull grooves by the grippingmember, thereby determining a first extent or a second extent ofrelative engagement, with the first extent being greater than the secondextent, if the first extent is detected then automatically applying therelative axial force between the gripping member and the swage anvil ofthe first magnitude, thereby swaging the collar into the locking groovesand clamping the workpieces together via the pin and the collar under afinal clamp load, automatically preventing the application of therelative axial force of the first magnitude unless the first extent ofrelative threaded engagement of the pull grooves by the gripping memberis automatically detected, if the first extent is not detected but thesecond extent is detected then automatically applying a relative axialforce of the second magnitude between the gripping member and the swageanvil, thereby pulling the workpieces together under an initial clampload, the second magnitude being less than that at which initiation ofswaging of the collar into the lock grooves of the pin occurs, and afterapplication of the relative axial force of the second magnitude applyinga rotary force, thereby threading the gripping member further onto thepull groove portion and if the first extent is detected thenautomatically applying the relative axial force between the grippingmember and the swage anvil of the first magnitude, automaticallypreventing the application of the relative axial force of the secondmagnitude unless the second extent of relative threaded engagement ofthe pull grooves by the gripping member is automatically detected. 13.The fastening system of claim 12 with the method of setting the fastenerfurther comprising:automatically halting the step of progressivelyengaging the pull grooves and automatically preventing the applicationof the relative axial force of the first magnitude unless the firstextent of threaded engagement has been detected within a predeterminedtime period.
 14. The fastening system of claim 12 with the method ofsetting the fastener further comprising:automatically unthreading thegripping member from the pull grooves if the preselected second extentof threaded engagement has not been attained by the gripping memberwithin a predetermined time period.
 15. The fastening system of claim 12with the method of setting the fastener further comprising:automaticallyunthreading the gripping member from the pull grooves if the preselectedsecond extent of threaded engagement has not been attained by thegripping member within a predetermined time period, automaticallyhalting the step of progressively engaging the pull grooves andautomatically preventing the application of the relative axial force ofthe first magnitude unless the first extent of threaded engagement hasbeen detected within a predetermined time period.
 16. The fasteningsystem of claim 12 with the method of setting the fastener furthercomprising:automatically unthreading the gripping member from the pullgrooves if the first extent of threaded engagement has not been attainedby the gripping member after detection of the second extent of threadedengagement and the automatic application of the relative axial force ofsecond magnitude has been made a preselected number of times.
 17. Thefastening system of claim 12 with the method of setting the fastenerfurther comprising:automatically unthreading the gripping member fromthe pull grooves if the first extent of threaded engagement has not beenattained by the gripping member after detection of the second extent ofthreaded engagement and the automatic application of the relative axialforce of second magnitude has been made.
 18. In a fastening system forsecuring a plurality of workpieces with a multi-piece swage typefastener with the workpieces including an inner workplace and at leastone outer workpiece,the fastener comprising a pin member and a tubularcollar and adapted to be set by a relative axial force therebetween, thepin member having an elongated pin shank with a locking groove portionon the pin shank, means operatively connecting the pin shank in loadbearing relationship with the inner workplace and with the pin shankadapted to extend through an aligned opening in the outer workpiece, thepin shank having a pull portion comprising a plurality of generallycircumferentially extending pull grooves, the pull portion located atthe terminal end of the pin shank with the pull grooves defined by athread form, the tubular collar adapted to be located on the pin shanksurrounding the locking grooves with the pull grooves being accessibleat an outer end of the collar, the method of setting the fastenercomprising:progressively threadably engaging the pull grooves generallyone at a time by a gripping member, engaging the collar by a swage anvilas the pull grooves are threadably engaged by the gripping member, theswage anvil adapted to engage the collar and swage it into the lockinggrooves in response to a relative axial force of a first magnitudeapplied between the pin member and the collar by the gripping member andthe swage anvil or alternatively and prior to applying the relativeaxial force of the first magnitude applying a relative axial force of asecond magnitude being less than the first magnitude to pull theworkpieces together, automatically detecting the extent of relativeengagement of the pull grooves by the gripping member, therebydetermining a first extent or a second extent of relative engagement,with the first extent being greater than the second extent, if the firstextent is detected then automatically applying the relative axial forcebetween the gripping member and the swage anvil of the first magnitude,thereby swaging the collar into the locking grooves and clamping theworkpieces together via the pin and the collar under a final clamp load,automatically preventing the application of the relative axial force ofthe first magnitude unless the first extent of relative threadedengagement of the pull grooves by the gripping member is automaticallydetected, if the first extent is not detected but the second extent isdetected then automatically applying a relative axial force of thesecond magnitude between the gripping member and the swage anvil,thereby pulling the workpieces together under an initial clamp load, thesecond magnitude being less than that at which initiation of swaging ofthe collar into the lock grooves of the pin occurs, and afterapplication of the relative axial force of the second magnitude applyinga rotary force, thereby threading the gripping member further onto thepull groove portion and if the first extent is detected thenautomatically applying the relative axial force between the grippingmember and the swage anvil of the first magnitude, automaticallypreventing the application of the relative axial force of the secondmagnitude unless the second extent of relative threaded engagement ofthe pull grooves by the gripping member is automatically detected,automatically halting the step of progressively engaging the pullgrooves and automatically preventing the application of the relativeaxial force of the first magnitude unless the first extent of threadedengagement has been detected within a predetermined time period,automatically unthreading the gripping member from the pull grooves ifthe preselected second extent of threaded engagement has not beenattained by the gripping member within a predetermined time period,automatically unthreading the gripping member from the pull grooves ifthe first extent of threaded engagement has not been attained by thegripping member after detection of the second extent of threadedengagement and the automatic application of the relative axial force ofsecond magnitude has been made a preselected number of times.